Performance-based link management communications

ABSTRACT

Disclosed herein are system, method, and computer program product embodiments for utilizing parallel links to improve sub-network availability and latency performance for ATC traffic. An embodiment operates by receiving a generated message. The type of the generated message is determined, where the type is an air traffic control message or a non-air traffic control message. Based on the type of message, communication links are selected, where the communication links include parallel transmission links or a serial link. The method continues by copying the generated message and transmitting the copied message using the selected communication links. The method waits to receive an acknowledgement indicating receipt of the transmitted message. Upon identifying an acknowledgement, any of the copied messages not yet retransmitted are deleted.

RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.17/222,450, filed Apr. 5, 2021, which is a continuation of U.S.application Ser. No. 16/365,104, filed Mar. 26, 2019 (now U.S. Pat. No.10,972,175), which is a continuation of U.S. application Ser. No.14/827,733, filed on Aug. 17, 2015 (now U.S. Pat. No. 10,243,646), allentitled “Performance-Based Link Management Communications,” which areincorporated by reference herein in their entirety.

STATEMENT UNDER MPEP 310

The U.S. government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of Contract No.0215BB05AA, awarded by the FAA Data Communications Program.

FIELD OF THE INVENTION

Embodiments included herein generally relate to utilizing parallel linksin air traffic control communications. More particularly, embodimentsrelate to utilizing parallel links in a performance-based linkmanagement system to improve the sub-network availability and latencyperformance for air traffic control communication systems.

BACKGROUND

Air Traffic Control (ATC) depends upon secure and reliablecommunications between ground-based controllers and aircraft incontrolled and non-controlled airspace. In order to meet the needs ofsecure and reliable communication, the Aircraft CommunicationsAddressing and Reporting System (ACARS) protocol and the AeronauticalTelecommunications Network Open Systems Interconnection (ATN OSI)protocol were designed in the ATC data communication protocol stacks, toname a few. The ACARS protocol utilizes various sub-networks, such asVery High Frequency Data Link-Mode 2 (VDL-Mode 2), Plain Old ACARS (POAor VDL Mode 0/A), ACARS over AVLC, Inmarsat (SATCOM), Iridium (SATCOM),and High Frequency Data Link (HFDL), that may be used to transmit themessages. Currently, the United States uses the ACARS based protocol,first deployed in 1978. Although there are many types of ACARS protocolsavailable, the United States specifically uses the Future Air NavigationSystem (FANS) protocol. The FANS protocol provides a direct datacommunication link between the pilot in the aircraft and the air trafficcontroller at the ground-based controller.

In Europe, ATC data communication uses Link2000+, a type of ATN OSIprotocol also known as ATN B1 implementation using solely the VDL Mode 2sub-network. The International Civil Aviation Organization (ICAO)introduced the ATN OSI protocol around the year 2000, following thecertification of FANS in 1995. There was a general belief that the newerATN OSI was superior to the older FANS in terms of performance due tothe advancements in technology. In response, the Federal AviationAdministration declared the FANS protocol would transition to the ATNOSI protocol in the United States. The FAA decided to implement thistransition and wrote in the FAA Data Communications Program (DCP)documents comprising the Segment 1 (S1) Investment Analysis ReadinessDecision (IARD), the S1 Initial Investment Decision (IID) and the S1Final Investment Decision (FID) information pertaining to thistransition. However, the assumption that ATN OSI would be superior toFANS has proved to be premature.

Today, ATN OSI over VDL Mode 2 is experiencing technical issues inEurope including provider aborts and long delays.

Provider aborts occur in a communication system when there may be asustained loss of end-to-end connectivity, thus loss of availability.Even though these provider abort and long delay issues were observedsome time ago, they did not receive substantial attention untilrelatively recently.

European Technical groups were formed to investigate the technicalissues with the ATN OSI European data link. In 2014, the EuropeanAviation Safety Agency (EASA) released an investigation report ontechnical issues in the implementation of a European Rule of the ATN OSIover VDL Mode 2. EASA found the technical issues to be sufficientlycritical that the European Commission decided to postpone the ATN OSIdata link rule for 5 years, from 2015 to 2020. Given the complicatednature of the ATN OSI over VDL Mode 2 technical issues, whether they canbe completely fixed or not is an open issue.

In addition to ATN OSI technical issues, the FANS customized protocolalso suffers from delays associated with latency performance. In the ATNOSI network, provider aborts take place after a delay of longer than 6minutes. In the FANS network, there is no provider abort mechanism, soFANS does not have a provider abort issue, however the FANS protocolemploys a means to try other sub-networks, in series. FANS, thereforeallows longer delays, which suits strategic planning but which makes itimpractical for tactical operation. The performance issues in FANS andATN OSI prevent them from replacing voice to become a primary ATCcommunication for time critical exchanges. Accordingly, there is a needfor improvement in air traffic control communications availability andlatency performance.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated herein and form a part of thespecification.

FIG. 1 is a block diagram of an air traffic control communication systemproviding a plurality of parallel data links between the aircraft andthe ground station, according to an example embodiment.

FIG. 2 is a block diagram of a performance-based link management systemthat includes multiple transceivers, a router and multiple externalsensors, according to an example embodiment.

FIG. 3 is a block diagram of a performance-based link management systemthat includes multiple transceivers and a Ground Station Command Center,according to an example embodiment.

FIG. 4 is a flowchart illustrating a process for transmitting ATC andnon-ATC messages from the performance-based link management system,according to an example embodiment.

FIG. 5 is a flowchart illustrating a process for receiving ATC andnon-ATC messages at the performance-based link management system,according to an example embodiment.

FIG. 6 is a flowchart illustrating a process for transmitting ATCmessages and receiving acknowledgements at the performance-based linkmanagement system, according to an example embodiment.

FIG. 7 is a flowchart illustrating a process for transmitting non-ATCmessages and receiving acknowledgements at the performance-based linkmanagement system, according to an example embodiment.

FIG. 8 is a flowchart illustrating an offline process for calculatingthe number of parallel links and storing in a policy table at theperformance-based link management system, according to an exampleembodiment.

FIG. 9 is an example computer system useful for implementing variousembodiments.

In the drawings, like reference numbers generally indicate identical orsimilar elements. Additionally, generally, the left-most digit(s) of areference number identifies the drawing in which the reference numberfirst appears.

SUMMARY

Provided herein are embodiments for performance-based link managementsystems that solve issues of existing systems (such as sub-networkavailability and latency performance) by utilizing parallel links.

An embodiment includes a method for utilizing parallel links in aperformance-based link management system. The method includes receivinga generated message, determining a type of the received message, whetherthe type is an air traffic control message or a non-air traffic controlmessage. Based on the type of message, the method selects communicationlinks comprising a plurality of parallel transmission links or a seriallink. The method copies the generated message and transmits the copiedmessage using the selected communication links, and waits to receive anacknowledgement indicating receipt of the transmitted message. Uponidentifying the acknowledgement, the method deletes any of the copiedmessages not yet retransmitted.

Another embodiment includes a system having a router processor that isoperable to receive a generated message. The router processor determinesthe type of the generated message, whether the type is an air trafficcontrol message or a non-air traffic control message. Based on the typeof message, the router processor selects communication links comprisinga plurality of parallel transmission links or serial links. The routerprocessor then copies the generated message and transmits the copiedmessage using the selected communication links via a transmitter. Therouter processor waits to receive an acknowledgement of the transmittedmessage and upon identifying the acknowledgement from a receiver, any ofthe copied messages not yet retransmitted are deleted.

A further embodiment includes a tangible computer-readable medium havingstored therein instructions for execution by one or more processors toperform a method for utilizing parallel links in a performance-basedlink management system. The method includes receiving a generatedmessage, determining a type of the received message, whether the type isan air traffic control message or a non-air traffic control message.Based on the type of message, the method selects communication linkscomprising a plurality of parallel transmission links or a serial link.The method copies the generated message and transmits the copied messageusing the selected communication links, and waits to receive anacknowledgement indicating receipt of the transmitted message. Uponidentifying the acknowledgement, the method deletes any of the copiedmessages not yet retransmitted.

Further features and advantages of the embodiments disclosed herein, aswell as the structure and operation of various embodiments, aredescribed in detailed below with reference to the accompanying drawings.It is noted that the invention is not limited to the specificembodiments described herein. Such embodiments are presented herein forillustrative purposes only. Additional embodiments will be apparent to aperson skilled in the relevant art based on the teachings containedherein.

DETAILED DESCRIPTION

Embodiments of performance-based link management (PBLM) address existingissues with ATC communication customizable protocols. As ATCcommunication currently exists, existing ATC communication protocolstacks, including FANS, ATN OSI, Internet Protocol Suite (IPS), andInternet Protocol (IP) Tunneling, are not performance-based. Inaddition, these existing ATC communication protocol stacks use seriallink transmission for both ATC and non-ATC traffic, i.e., transmitting amessage using one link at a time, and moving to the next link when theprevious link exhausts the link's retries. By using theperformance-based link management system, the ATC messages aresimultaneously transmitted using parallel links based on ATC performancerequirements, e.g., Required Availability, and Required CommunicationTechnical Performance (RCTP), using the pre-existing transceivers on theaircraft and at the ground-based controller with updates to theirconfiguration.

Embodiments enable a performance-based link management system to utilizeparallel links in order to more quickly and effectively transmit andreceive ATC messages. There are advantages for using simultaneousparallel links in ATC communication. One advantage is significantlyincreasing the sub-network availability. Sub-network availability refersto the availability of the transceiver radios (i.e., whether thetransceiver radios are not transmitting, receiving messages or in adeactivated state). Another advantage for using simultaneous parallellinks is reducing the sub-network technical delay multi-fold. Thesub-network technical delay refers to the network latency of thetransmission data links. Another advantage for using simultaneousparallel links is robustness to sub-network Denial-of-Service (DoS)attacks. In a parallel communication network, single linkDenial-of-Service attack may degrade the network latency performance,but the message may still transmit to the message's desired destination.

FIG. 1 illustrates an embodiment of an air traffic control communicationsystem 100 for providing a plurality of parallel data links between anaircraft 102 and ground station 110. Air traffic control communicationsystem 100 includes aircraft 102, the aircraft's PBLM system 104,satellite 106, the ground station's PBLM system 108, the ground station110, and a plurality of parallel links between the aircraft's PBLMsystem 104 and the ground station's PBLM system 108. Each of theaircraft's PBLM system 104 and the ground station's PBLM system 108 maybe implemented using one or more processors, according to an embodiment.Although the aircraft's PBLM system 104 and the ground station's PBLMsystem 108 are shown to be external to the aircraft 102 and groundstation 110, respectively, the aircraft's PBLM system 104 is housedinside of aircraft 102 and ground station's PBLM system 108 is housedinside of ground station 110.

In an embodiment, in the air traffic control communication system 100,when the aircraft's PBLM system 104 transmits ATC or the non-ATCmessages, the aircraft's PBLM system 104 enables the configuration forthe parallel links based on the ATC performance requirements, e.g.,Required Availability, and/or RCTP. In an embodiment, the groundstation's PBLM system 108 also enables the configuration for theparallel links based on the ATC performance requirements whentransmitting ATC or non-ATC messages. In an alternative embodiment, airtraffic control communication system 100 may be configured in an oceanicenvironment. In alternative embodiments, the aircraft may be on therunway, may be flying to the aircraft's final destination at aparticular altitude, or may be climbing upwards or descending. Further,another embodiment includes a mobile vehicle environment.

In an embodiment, the aircraft's PBLM system 104 may enable the use of aSatellite Communications (SATCOM) link 105 to transmit either the ATC ornon-ATC messages to the satellite 106. The satellite 106 transmits thereceived ATC or non-ATC messages from link 105 to the ground station'sPBLM system 108 over SATCOM link 107. In an embodiment, the aircraft'sPBLM system 104 may enable the use of a POA link 109 to transmit the ATCor non-ATC messages to the ground station's PBLM system 108. In anembodiment, the aircraft's PBLM system 104 may enable the use of aVDL-M2 link 111 to transmit ATC or non-ATC messages to the groundstation's PBLM system 108. In an embodiment, the ground station's PBLMsystem 108 may use the same SATCOM, POA, and VDL-M2 link to transmit ATCor non-ATC messages to the aircraft's PBLM system 104.

The aircraft's PBLM system 104 may not be limited to the ACARSsub-networks of SATCOM link 105, SATCOM link 107, POA link 109, and/orVDL-M2 link 111. In embodiments, the aircraft PBLM system 104 may usedifferent sub-networks such as but not limited to Inmarsat, Iridium, anddifferent variations of HFL. The ground station's PBLM system 108 maynot be limited to the ACARS sub-networks of SATCOM link 105, SATCOM link107, POA link 109, and/or VDL-M2 link 111. In an embodiment, the groundstation PBLM system 108 may use different sub-networks such as but notlimited to Inmarsat, Iridium, and HFDL. The aircraft's PBLM system 104and the ground station's PBLM system 108 may have the same or differentnumber of parallel links for a particular embodiment. To meet therequirement of S1 DCP for a required 0.9999 availability, the number ofparallel links needed may be at least 3, in an embodiment. Inalternative embodiments, more or less links may be used per particularapplications based on external requirements or environmentalconfigurations.

An advantage to using parallel links for transmission in the air trafficcontrol communication system 100 includes increasing the sub-networkavailability. To understand how parallel links increase the sub-networkavailability, assume n simultaneous parallel links are used to transmita message. Assume the availabilities of the n simultaneous parallellinks are denoted by A₁, A₂ . . . A_(n). The overall availability A ofthe n simultaneous parallel links may be calculated by using the productoperator as follows:

$\begin{matrix}{A = {1 - {\underset{i = 1}{\prod\limits^{n}}\left( {1 - A_{i}} \right)}}} & (1)\end{matrix}$

In Equation 1, assume the availability A of each link is the same, i.e.,0.99. In this case, the unavailability is 1−A, or 0.01. The availabilityof two parallel links (where n=2) is 0.9999. This reduces theunavailability 100 times or to 10⁻⁴. The availability for three parallellinks is 0.999999, which reduces the unavailability 10000 times or to10⁻⁶. This shows a direct relationship between the number of links andthe availability. In order to meet the requirements of the DCP S1report, the sub-network availability has to meet a required availabilityof 0.9999. If three parallel links or more are used, as shown usingEquation 1, this requirement is met.

Another advantage of using simultaneous links may be the ability of thesimultaneous links to defeat DoS attacks. DoS attacks are attempts tomake a machine or network resource unavailable to the machine's intendedusers. The DoS attack will affect the ability for ATC communication totransmit information over single links. However, by using n parallellinks even in the midst of DoS attacks, the messages can still reliablyreach the message's destination.

FIG. 2 illustrates components within the aircraft's PBLM system 104 inthe aircraft 102, according to an example embodiment. In an embodiment,PBLM system 200 may incorporate features to transmit applicationmessages and receive message data in parallel. These features includeremote avionic applications 201 and a communication system 203.Generally, applications pass data to an antenna via a router. In anembodiment, the router appears as equipment known as a CommunicationsManagement Unit (CMU) 208 in the communications system 203. The CMU 208utilizes a processor 210 which may be configured to parallelize theapplications' messages to each of the suitable transmission mediums(SATCOM, POA, VDL-M2) through the transceivers 212 and antennas 214. TheCMU 208 has the capability to transmit data to the ground station 110and receive data from the ground station's PBLM system 108. Thecomponents of the PBLM system 200 illustrate the architecture of aconventional ACARS platform in the aircraft 102.

The CMU 208 gathers information relating to the airline from the remoteavionic applications 201. The remote avionic applications 201 passapplication specific information to the CMU 208 in which to transmit,according to an embodiment. The remote avionic applications 201 mayinclude an Aircraft Conditioning Monitor System (ACMS) module 202 usedfor monitoring and controlling the status of the onboard systems andequipment, as well as variations in the flight conditions and to theoperation of the flight equipment. The remote avionic applications 201may also include an Air Traffic Control module (ATC) 204 which iscapable of receiving and transmitting any pertinent information for airtraffic control. Lastly, a Central Maintenance Computer System (CMCS)module 206 may be used for collecting and analyzing complete maintenanceinformation. The CMCS module 206 collects, consolidates and reportsissues to aid flight crew and maintenance personnel in maintenanceprocedures.

According to an example embodiment, the PBLM system 200 may also includetransceivers 212-1 through 212-n, in which those transceivers 212 mayuse SATCOM, Very High Frequency (VHF), and High Frequency (HF) datalinks. These transceivers 212 and antennas 214 operate over differentfrequency ranges and may transmit and receive in parallel to increasereliability. Parallel transmission and reception may help with latency,provider abort delays, and increase the availability of each of thetransceivers 212. The antennas 214 are attached to each of thetransceivers 212, where the antennas 214 range from 1 to n, one antennafor each transceiver 212. Because the CMU 208 may be configured to passthe data messages from the remote avionic applications 201 totransceivers 212 in FIG. 2 , the antennas 214 connected to eachtransceiver 212 may be both passive and active antennas 214, in whichthey both receive and transmit the data, respectively, according to anembodiment. In an embodiment, one transceiver 212-1 may be connected toone antenna 214-1 to transmit the data and a separate antenna 214-2 maybe connected to the same transceiver 212-1 for receiving data.

FIG. 3 illustrates an embodiment of the performance-based linkmanagement system 108. FIG. 3 is similar to FIG. 2 , but shows a GroundStation Command Center 302 instead of the remote avionics application201. The Ground Station Command Center 302 creates the application datato transmit. The application data may include instructions to ping theaircraft to ensure a healthy ACARS communication link, voice and textmessages to the aircraft pilots, according to embodiments.

FIG. 4 illustrates a method 400 for transmitting an ATC message or anon-ATC message in the performance-based link management system 200/300,according to an example embodiment. Method 400 may be performed withmultiple embodiments of the performance-based link management system200/300, including within air traffic control communication system 100.Process 400 may be performed by processing logic that may includehardware, software, or a combination thereof. In an embodiment, steps inFIG. 4 may not need to be performed in the order shown, as one skilledin the art would understand. In an embodiment, method 400 may beadjusted to transmit ATC and non-ATC messages in parallel if theapplications generated the ATC and non-ATC message simultaneously.

In step 402, the remote avionic application 201 generates a message totransmit. In an embodiment, either the ACMS 202, the ATC 204, or theCMCS 206 may generate a message to transmit. The message may be createdbased on a specific need of the aircraft 102.

In step 404, the performance-based link management system 200/300determines whether the generated message is an ATC message or a non-ATCmessage. In an embodiment, an Airline Operation Center (AOC) message isa type of non-ATC message. An AOC message may include informationregarding fuel weight and balance information of the aircraft 102. AnAOC message may also indicate whether the aircraft 102 is out of thegate, whether the aircraft is taking off from the ground, whether theaircraft is on the ground, or whether the aircraft is in the gate.Generally, these AOC messages do not need to meet the safety andperformance requirements of ATC messages, and instead track the aircraft102's status. Air traffic control communication utilizes ATC messagescomprising required performance metrics. ATC messages are generallycommunicated between the aircraft 102 and the ground station 110,according to an embodiment.

If the message is an ATC message, step 406 is performed. In step 406,the CMU 208 may select a number of parallel links to transmit the ATCmessage. The selection of parallel links may be based on a number offactors, according to an embodiment. These factors may include airlinerequirements, the RCTP, the number of transceivers available, theavailability requirement, etc. As an example of airline requirements, agiven airline may designate particular links for ATC and non-ATCmessages. As an example of transceivers being available, links may beselected if their corresponding transceivers are not in use. An exampleof an availability requirement and/or RCTP may be a requirement set by agovernment regulation. Calculation of the number of parallel linksrequired to meet those factors may be performed in an offline processand will be explained in a further detail below.

If it is determined in step 404 the message is a non-ATC message, thenstep 408 is performed. In step 408, the CMU 208 may select a traditionalserial link to save costs and bandwidth to transmit the non-ATC message.The reason to use the traditional serial link for a non-ATC message isthat non-ATC messages are not as critical to aircraft 102 safety as ATCmessages.

In step 410, the CMU 208 transmits the non-ATC message or the ATCmessage by the serial or the parallel links based on the decision madeby step 404, according to an embodiment. The CMU 208 routes the messageto transceivers 212, which transmits the message via antennas 214,according to an embodiment.

FIG. 5 illustrates a method 500 for receiving an ATC or a non-ATCmessage in the performance-based link management system 200/300,according to an example embodiment. Method 500 may be performed withmultiple embodiments of the performance-based link management system200/300, including within air traffic control communication system 100.Process 500 may be performed by processing logic that may includehardware, software, or a combination thereof. In an embodiment, steps inFIG. 5 may not need to be performed in the exact order shown, as oneskilled in the art would understand. In an embodiment, method 500 may beadjusted to receive ATC and non-ATC messages in parallel if the ATC andnon-ATC messages are transmitted simultaneously.

In step 502, the performance-based link management system 200/300 mayreceive data via antennas 214, according to an embodiment. In step 504,the CMU 208 determines if the data is an ATC or a non-ATC message.

Step 506 is performed if the data is not an ATC message. In step 506,the performance-based link management system 200/300 sends the non-ATCmessage to the Ground Station Command Center 302 by way of the CMU 208.Once the CMU 208 receives the message, the CMU 208 sends the message toACMS 202, ATC 204, CMCS 206, or the Ground Station Command Center 302,where the received non-ATC message may be acted upon accordingly,according to an embodiment.

In step 508, the performance-based link management system 200/300 maysend an acknowledgement across the selected links to increase the chanceof receipt by the transmitting entity. Acknowledgements are thehand-shaking mechanism used to give the transmitting and receive sidesknowledge that the message, either ATC or non-ATC, has been transmittedand received successfully.

If it is determined in step 504 that the data is an ATC message, thenstep 512 is performed. Step 512 verifies if the ATC message is aduplicate of a previously received ATC message. According to anembodiment, the ATC messages are prepended with a sequence numberin-order to keep track of each ATC message transmitted at thetransmission side. Prepending a sequence number gives security totransmissions of ATC messages. Also, it is possible from this sequencenumber to determine if a received ATC message is a duplicate of apreviously received ATC message. This is further described below.

If the ATC message is a duplicate, then the message may be discarded andfiltered in step 514 by CMU 208. This ensures the same ATC message isnot processed multiple times by the performance-based link managementsystem 200/300.

If the ATC message is not a duplicate, step 518 is performed. In step518, the CMU 208 updates the states for each link. The CMU 208 keepstrack of the states for each of the links on the received side of theperformance-based link management system 200/300. The CMU 208 monitorseach link by storing each received sequence number and comparing thecurrent received sequence number to previously received sequencenumbers. The CMU 208 discards any duplicate ATC message if the currentreceived sequence number matches any of the previously received sequencenumbers.

In step 520, the received ATC message may be sent to the remote avionicapplications 201 or the Ground Station Command Center 302 by way of theCMU 208.

In step 522, the performance-based link management system 200/300 maysend back an acknowledgement across the selected links, according to anembodiment. The acknowledgements may be sent back across all of theselected links so the transmitting side that transmitted the receivedATC message may have a better chance of receiving the acknowledgment,instead of transmitting the acknowledgement over one link.

FIG. 6 illustrates a more detailed method of method 400 for transmittingan ATC message in the performance-based link management system 200/300,according to an example embodiment. Specifically, FIG. 6 illustratesstep 403 of FIG. 4 in greater detail. The method of FIG. 6 may beperformed with multiple embodiments of the performance-based linkmanagement system 200/300, including within air traffic controlcommunication system 100 and method 400. The method of FIG. 6 may beperformed by processing logic that may include hardware, software, or acombination thereof. In an embodiment, steps in FIG. 6 may not need tobe performed in the exact order shown, as one skilled in the art wouldunderstand.

In step 602, the CMU 208 may select a number of parallel links to use totransmit the ATC message. The selection of parallel links may be basedon a number of factors, according to an embodiment. These factors mayinclude but are not limited to airline requirements, the RCTP, thenumber of transceivers available and the availability requirement.Calculation of the number of parallel links required to meet thesefactors may be done in an offline step and will be explained furtherbelow.

In step 604 the CMU 208 may prepend a sequence number to the ATC messagebeing transmitted. A sequence number may be prepended to each ATCmessage in order to reliably keep track of each ATC message transmitted.When a new message is generated, the sequence number may be incrementedby one.

In step 606, the CMU 208 may create n copies of the ATC message. The CMU208 may queue the n copied ATC messages for transmission.

In step 608, the CMU 208 routes the n copied ATC messages to theplurality of n parallel links chosen by step 602. More specifically, atstep 608, the CMU 208 may route each of the n messages to thetransceiver 212, according to an embodiment. The transceiver 212 maymodulate, convert to RF, and send the up-converted ATC message to eachof the n antennas 214.

In step 610, the performance-based link management system 200/300 waitsa predetermined amount of time for an acknowledgement. Thispredetermined amount of time may be set based on the airlinerequirements, the availability requirements, the sub-network latencydelay requirement, or any combination thereof. If an acknowledgment isreceived within the predetermined time limit, step 612 is performed.

In step 612, the CMU 208 stores the acknowledgements for the associatedATC message so that the ATC message is not retransmitted.

In step 614, any remaining, not yet transmitted queued copies of themessage (from step 606) are deleted. It may be the case, however, thatone or more copies of the message may be in the process of beingtransmitted. These duplicate message transmissions are handled by thereceiver system in steps 512 and 514, as discussed above.

If an acknowledgement was not received in the predetermined time in step610, the CMU 208 may check the status of all n links in the parallellink system in step 618. In an embodiment, the CMU 208 will check to seeif any link has reached the link's max retry attempt. In an embodiment,the max retry attempt corresponds to the number of times a link will tryto transmit the same message. In an embodiment, the max retry attemptnumber may be policy configurable and may be set based on airplanerequirements and the type of message being transmitted. If none of thelinks have met their max retry attempt, control returns to step 608.Otherwise, step 620 is performed.

In step 620, any selected links at their max retry attempt may be madeavailable for the transmission of other ATC or non-ATC messages.

In step 622, the CMU 208 determines if all the selected links are attheir max retry attempt. If they are all at their max retry attempt,then no links are available for the current ATC message. Thus, in step624, the CMU 208 deletes any remaining queued copies of messages fromstep 606. Further, the CMU 208 releases the selected links forsubsequent transmission of other ATC or non-ATC messages.

Otherwise, the CMU 208 may use the remaining available links tore-transmit the ATC message. Thus, in step 628, the CMU 208 selects theremaining links available for re-transmission. The CMU 208 updates itssystem's link states reflecting the parallel links that are nowavailable for other non-ATC/ATC messages and the remaining links thatmay be used to re-transmit the ATC message.

FIG. 7 illustrates a more detailed method of method 400 for transmittinga non-ATC message, according to an example embodiment. Specifically,FIG. 7 illustrates step 405 of FIG. 4 in greater detail. The method ofFIG. 7 may be performed with multiple embodiments of theperformance-based link management system 200/300, including within airtraffic control communication system 100 and method 400. The method ofFIG. 7 may be performed by processing logic that may include hardware,software, or a combination thereof. In an embodiment, steps in FIG. 7may not need to be performed in the exact order shown, as one skilled inthe art would understand.

In step 702, the CMU 208 may check to see what links are available totransmit. This determination may be based on whether the transceiver 212and antenna 214 are already transmitting or in the process of receivingdata.

In step 704, the CMU 208 checks what the link preference may be fortransmitting a non-ATC message. In an embodiment, a link preference fortransmitting a non-ATC message may be VHF, HF, and SATCOM or anycombination thereof. In an embodiment, the link preference fortransmitting a non-ATC message may be at the discretion of the airline.

In step 706, the CMU 208 selects the link to transmit the non-ATCmessage based on the link preference from step 704 and what links areavailable in step 702.

In step 708, the CMU 208 may prepend a sequence number to the non-ATCmessage being transmitted. A sequence number may be prepended to eachnon-ATC message in-order to reliably keep track of each non-ATC messagetransmitted. When a new message is generated, the sequence number may beincremented by one.

In step 710, the CMU 208 routes the non-ATC message with the prependedsequence number to the preferred available link chosen by step 706. Morespecifically, the CMU 208 routes the non-ATC message to the transceiver212 for transmission.

In step 712, the performance-based link management system 200/300 waitsa predetermined amount of time for an acknowledgement. Thispredetermined amount of time may be set based on the airlinerequirements, the availability requirements, the sub-network latencydelay requirement, or any combination thereof. If the CMU processor 210receives the acknowledgment received within the predetermined timelimit, the process ends.

If an acknowledgement was not received in the predetermined time in step712, the CMU 208 may check the status of the preferred link in step 716.In an embodiment, the CMU 208 will check to see if the preferred linkhas reached the link's max retry attempt. The same requirements for themax retry attempt may apply in step 716 as described previously in step618. If the preferred link has not yet met the link's max retry attempt,control returns to step 710. Otherwise, step 718 is performed.

In step 718, the CMU 208 makes the preferred link available for thetransmission of other ATC or non-ATC messages.

In step 720, the CMU 208 determines if all the preferred links for theairline are being used for other ATC or non-ATC messages. If all thelinks are being used for other messages, then no links are available forthe current non-ATC message and in step 722, the process ends.

Otherwise, the CMU 208 may select the next preferred link that isavailable to re-transmit the non-ATC message in step 724. The CMU 208updates its system reflecting the links that are now available for othernon-ATC/ATC messages and the remaining links that may be used tore-transmit the non-ATC message.

FIG. 8 illustrates a method 800 for calculating the number of parallellinks based on, for example, airline requirements, the RCTP, the numberof transceivers available, or any combination thereof, according to anexample embodiment. Method 800 may be performed with multipleembodiments of the performance-based link management system 200/300,including within air traffic control communication system 100. Process800 may be performed by processing logic that may include hardware,software, or a combination thereof. In an embodiment, steps in FIG. 8may not need to be performed in the exact order shown, as one skilled inthe art would understand.

An advantage for using parallel links for transmission in theperformance-based link management system 200/300 is to reducesub-network latency. To understand how parallel links reduce sub-networklatency, assume the latencies of the n parallel links are denoted by x₁,x₂, . . . x_(n). The latency y of n simultaneous parallel links may bethe minimum latency of the aggregation of the n simultaneous parallellinks. An equation to determine the minimum link latency may be shown asfollows.

y=min(x ₁ ,x ₂ , . . . ,x _(n))  (2)

Assume the latencies of the n parallel links, i.e., x₁, x₂, . . . ,x_(n), are independent random variables. The Cumulative DistributionFunction (CDF) of the n parallel links are denoted by F_(X1)(t),F_(X2)(t), . . . F_(Xn)(t), wherein the CDF F_(Y)(t) of n simultaneousparallel links can be calculated using an equation as follows:

$\begin{matrix}{{F_{Y}(t)} = {1 - {\prod\limits_{i = 1}^{n}\left\lbrack {1 - {F_{Xi}(t)}} \right\rbrack}}} & (3)\end{matrix}$

Using the CDF F(t), the (100×p)-th percentile t_(p), can be calculatedas follows:

t _(p) =F ⁻¹(p)  (4)

In an embodiment, assuming each single link has the same latencydistribution, Equations 3 and 4 indicate that the 99.9^(th) percentileof latency for a single link is about 95 seconds, whereas the 99.9^(th)percentile of latency for two parallel links is about 15 seconds. This 6fold latency reduction from one link to two parallel links greatlyreduces the sub-network latency delay. From two parallel links to threeparallel links, Equations 3 and 4 indicate the 99.9^(th) percentile oflatency for three parallel links is about 7 seconds, an even greaterimprovement from the single link. In an embodiment, the probabilitydensity function could be used as well to calculate the latency for aparticular link, which would further show that parallel links caneffectively shorten the network latency for ATC communications.

In an embodiment, step 802 may be an offline processing step performedby the CMU 208. The offline processing step may have requirements tomeet in terms of the availability A and the RCTP of the correspondingATC service. In step 804, the number of parallel links required arecalculated based on the availability A and latency CDF F_(Y)(t) of theselected available parallel links. In an embodiment, the two equationsused to calculate the availability are Equation 1 and Equation 3(above). In an embodiment, once the results are calculated, in order toselect the required number of available links, there are threerequirements that should be met:

A>A _(Req)  (5)

t _(0.95) =F _(Y) ⁻¹(0.95)<T _(0.95)  (6)

t _(0.999) =F _(Y) ⁻¹(0.999)<T _(0.999)  (7)

Equations 5, 6 and 7 represent the requirements needed for calculatingthe parallel links. In Equation 5, A corresponds to the calculatedavailability from Equation 1. A_(Req) corresponds to the requiredavailability set forth by the S1 DCP. In Equation 6, the T_(0.95) may bethe required 95^(th) percentile latency. Also in Equation 5, t_(0.95)may be (100×p)-th percentile for a latency CDF distribution. In Equation7, the T_(0.999) may be the required 99.9^(th) percentile latency. Alsoin Equation 7, t_(0.999) may be the (100×p)-th percentile for a latencyCDF distribution. In the above, p may be the percentage of the link'sdistribution.

In step 806, the number of parallel links calculated in step 804 arestored in a policy table. The policy table may be stored in memory inthe CMU 208. During transmission of an ATC message as described above,the number of parallel links may be retrieved from the policy table inthe database.

FIG. 9 is an example computer system to that may be used to implementaspects of the systems illustrated in FIGS. 1-3 , or which may bespecially programmed to implement aspects of the methods illustrated inFIGS. 4-8 .

Various embodiments can be implemented, for example, using one or morewell-known computer systems, such as computer system 900 shown in FIG. 9. Computer system 900 can be any well-known computer capable ofperforming the functions described herein.

Computer system 900 includes one or more processors (also called centralprocessing units, or CPUs), such as a processor 904. Processor 904 isconnected to a communication infrastructure or bus 906.

Computer system 900 also includes user input/output device(s) 903, suchas monitors, keyboards, pointing devices, etc., which communicate withcommunication infrastructure 906 through user input/output interface(s)902.

Computer system 900 also includes a main or primary memory 908, such asrandom access memory (RAM). Main memory 908 may include one or morelevels of cache. Main memory 908 has stored therein control logic (i.e.,computer software) and/or data.

Computer system 900 may also include one or more secondary storagedevices or memory 910. Secondary memory 910 may include, for example, ahard disk drive 912 and/or a removable storage device or drive 914.Removable storage drive 914 may be a floppy disk drive, a magnetic tapedrive, a compact disk drive, an optical storage device, tape backupdevice, and/or any other storage device/drive.

Removable storage drive 914 may interact with a removable storage unit918. Removable storage unit 918 includes a computer usable or readablestorage device having stored thereon computer software (control logic)and/or data. Removable storage unit 918 may be a floppy disk, magnetictape, compact disk, DVD, optical storage disk, and/any other computerdata storage device. Removable storage drive 914 reads from and/orwrites to removable storage unit 918 in a well-known manner.

According to an exemplary embodiment, secondary memory 910 may includeother means, instrumentalities or other approaches for allowing computerprograms and/or other instructions and/or data to be accessed bycomputer system 900. Such means, instrumentalities or other approachesmay include, for example, a removable storage unit 922 and an interface920. Examples of the removable storage unit 922 and the interface 920may include a program cartridge and cartridge interface (such as thatfound in video game devices), a removable memory chip (such as an EPROMor PROM) and associated socket, a memory stick and USB port, a memorycard and associated memory card slot, and/or any other removable storageunit and associated interface.

Computer system 900 may further include a communication or networkinterface 924. Communication interface 924 enables computer system xx00to communicate and interact with any combination of remote devices,remote networks, remote entities, etc. (individually and collectivelyreferenced by reference number xx28). For example, communicationinterface 924 may allow computer system 900 to communicate with remotedevices 928 over communications path 926, which may be wired and/orwireless, and which may include any combination of LANs, WANs, theInternet, etc. Control logic and/or data may be transmitted to and fromcomputer system 900 via communication path 926.

In an embodiment, a tangible apparatus or article of manufacturecomprising a tangible computer useable or readable medium having controllogic (software) stored thereon is also referred to herein as a computerprogram product or program storage device. This includes, but is notlimited to, computer system 900, main memory 908, secondary memory 910,and removable storage units 918 and 922, as well as tangible articles ofmanufacture embodying any combination of the foregoing. Such controllogic, when executed by one or more data processing devices (such ascomputer system 900), causes such data processing devices to operate asdescribed herein.

Based on the teachings contained in this disclosure, it will be apparentto persons skilled in the relevant art(s) how to make and use theinvention using data processing devices, computer systems and/orcomputer architectures other than that shown in FIG. 9 . In particular,embodiments may operate with software, hardware, and/or operating systemimplementations other than those described herein.

It is to be appreciated that the Detailed Description section, and notthe Summary and Abstract sections (if any), is intended to be used tointerpret the claims. The Summary and Abstract sections (if any) may setforth one or more but not all exemplary embodiments of the invention ascontemplated by the inventor(s), and thus, are not intended to limit theinvention or the appended claims in any way.

While the invention has been described herein with reference toexemplary embodiments for exemplary fields and applications, it shouldbe understood that the invention is not limited thereto. Otherembodiments and modifications thereto are possible, and are within thescope and spirit of the invention. For example, and without limiting thegenerality of this paragraph, embodiments are not limited to thesoftware, hardware, firmware, and/or entities illustrated in the figuresand/or described herein. Further, embodiments (whether or not explicitlydescribed herein) have significant utility to fields and applicationsbeyond the examples described herein.

Embodiments have been described herein with the aid of functionalbuilding blocks illustrating the implementation of specified functionsand relationships thereof. The boundaries of these functional buildingblocks have been arbitrarily defined herein for the convenience of thedescription. Alternate boundaries can be defined as long as thespecified functions and relationships (or equivalents thereof) areappropriately performed. Also, alternative embodiments may performfunctional blocks, steps, operations, methods, etc. using orderingsdifferent than those described herein.

References herein to “one embodiment,” “an embodiment,” “an exampleembodiment,” or similar phrases, indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it would be within the knowledge of persons skilled in therelevant art(s) to incorporate such feature, structure, orcharacteristic into other embodiments whether or not explicitlymentioned or described herein.

The breadth and scope of the invention should not be limited by any ofthe above-described exemplary embodiments, but should be defined only inaccordance with the following claims and their equivalents.

1. (canceled)
 2. A performance-based link management system configuredto manage communications of a vehicle, the performance-based linkmanagement system comprising: a remote management component comprising:a monitor system module configured to monitor status of an onboardsystem of the vehicle; and a central maintenance system configured tocollect maintenance information associated with the vehicle; acommunications system in communication with the remote managementcomponent, the communications system comprising: a communicationsmanagement unit configured to generate a plurality of parallel messagesfrom a message received from the remote management component, whereineach parallel message of the plurality of parallel messages is a copy ofthe message received from the remote management component; a pluralityof transceivers, wherein each transceiver in the plurality oftransceivers is configured to receive, from the communicationsmanagement unit, a parallel message of the plurality of parallelmessages; and a plurality of antennae in communication with theplurality of transceivers, wherein each antenna of the plurality ofantennae is configured to transmit the parallel message.
 3. Theperformance-based link management system of claim 1, wherein the vehicleis a mobile vehicle.
 4. The performance-based link management system ofclaim 1, wherein the vehicle is an aircraft.
 5. The performance-basedlink management system of claim 1, wherein the message received from theremote management component is transmitted from one of the monitorsystem module or the central maintenance system.
 6. Theperformance-based link management system of claim 1, wherein the remotemanagement component further comprises air traffic control moduleconfigured to: receive air traffic control information; and transmit anair traffic control message to the communications system.
 7. Theperformance-based link management system of claim 1, wherein thecommunications management unit is further configured to: calculate anumber of transceivers from the plurality of transceivers fortransmitting the plurality of parallel messages, wherein the calculatingfurther comprises: determine an overall availability of the number oftransceivers, wherein the number of transceivers is calculated based onthe overall availability being greater than an availability requirementfor transmitting the air traffic control message; select the number oftransceivers; copy the air traffic control message to produce theplurality of parallel messages, wherein the plurality of parallelmessages is based on the selected number of transceivers; and transmit,via a corresponding number of antennae from the plurality of antennae,the plurality of parallel messages using the selected number oftransceivers.
 8. The performance-based link management system of claim6, wherein selecting the number of transceivers comprises selecting atleast transceiver based on one or more of airline requirements, requiredcommunication technical performance and the availability requirement. 9.The performance-based link management system of claim 1, wherein theremote management component is a remote avionics application.
 10. Theperformance-based link management system of claim 1, wherein a firsttransceiver of the plurality of transceivers utilizes a satellitecommunications link, a second transceiver of the plurality oftransceivers utilizes a plain old aircraft communications addressing andreporting system (POA) link, and a third transceiver of the plurality oftransceivers utilizes a very high frequency data link-mode (VDL) link.11. The performance-based link management system of claim 9, wherein thefirst transceiver is configured to receive a first parallel message ofthe plurality of parallel messages from the communications managementunit, the second transceiver is configured to receive a second parallelmessage of the plurality of parallel messages from the communicationsmanagement unit, and the third transceiver is configured to receive athird parallel message of the plurality of parallel messages from thecommunications management unit.
 12. The performance-based linkmanagement system of claim 1, wherein the message received from theremote management component comprises at least one of the status of theonboard system of the vehicle and the maintenance information associatedwith the vehicle.
 13. A method by a performance-based link managementsystem configured to manage communications of a vehicle, comprising:monitoring, by a remote management component of the performance-basedlink management system, a status of an onboard system of the vehicle;collecting, by the remote management component, maintenance informationassociated with the vehicle; generating, by a communications managementunit of the performance-based link management system, a plurality ofparallel messages from a message received from the remote managementcomponent, wherein each parallel message of the plurality of parallelmessages is a copy of the message received from the remote managementcomponent; providing the plurality of parallel messages to a pluralityof transceivers, wherein each transceiver in the plurality oftransceivers is configured to receive, from the communicationsmanagement unit, a parallel message of the plurality of parallelmessages; and transmitting, by a plurality of antennae in communicationwith the plurality of transceivers, the plurality of parallel messages,wherein each antenna of the plurality of antennae is configured totransmit the parallel message.
 14. The method of claim 12, wherein thevehicle is a mobile vehicle.
 15. The method of claim 12, wherein thevehicle is an aircraft.
 16. The method of claim 12, wherein the messagereceived from the remote management component is transmitted from one ofthe monitor system module or the central maintenance system.
 17. Themethod of claim 12, wherein the remote management component furthercomprises an air traffic control module, and the method furthercomprising: receiving, by the air traffic control module, air trafficcontrol information; and transmitting, by the air traffic controlmodule, an air traffic control message to the communications system. 18.The method of claim 12, wherein a first transceiver of the plurality oftransceivers utilizes a satellite communications link, a secondtransceiver of the plurality of transceivers utilizes a plain oldaircraft communications addressing and reporting system (POA) link, anda third transceiver of the plurality of transceivers utilizes a veryhigh frequency data link-mode (VDL) link.
 19. A non-transitory tangiblecomputer-readable device having instructions stored thereon that, whenexecuted by at least one computing device, causes at least one computingdevice to perform operations comprising: monitoring, by a remotemanagement component of a performance-based link management system, astatus of an onboard system of a vehicle; collecting, by the remotemanagement component, maintenance information associated with thevehicle; generating, by a communications management unit of theperformance-based link management system, a plurality of parallelmessages from a message received from the remote management component,wherein each parallel message of the plurality of parallel messages is acopy of the message received from the remote management component;providing the plurality of parallel messages to a plurality oftransceivers, wherein each transceiver in the plurality of transceiversis configured to receive, from the communications management unit, aparallel message of the plurality of parallel messages; andtransmitting, by a plurality of antennae in communication with theplurality of transceivers, the plurality of parallel messages, whereineach antenna of the plurality of antennae is configured to transmit theparallel message.
 20. The non-transitory tangible computer-readabledevice of claim 18, wherein the vehicle is a mobile vehicle.
 21. Thenon-transitory tangible computer-readable device of claim 18, whereinthe vehicle is an aircraft.